Smart Materials Research at UAHuntsville W. Lin...Hybrid Linear/Rotary Actuator ... Smart Structures...
Transcript of Smart Materials Research at UAHuntsville W. Lin...Hybrid Linear/Rotary Actuator ... Smart Structures...
UAHuntsville Materials Science Faculty Research SymposiumDecember 05, 2012
Mark W. Lin, Ph.D.Associate Professor
Department of Mechanical and Aerospace EngineeringUniversity of Alabama in Huntsville
Huntsville, Alabama
Smart Materials Research at UAHuntsville
Boeing Seminar-2
Outline
Introduction Electrical Time Domain Reflectometry (ETDR) Distributed Strain Sensor
Impedance-Based Piezoelectric Sensor Hybrid Linear/Rotary Actuator
Shape Memory Alloy (Nitinol) Active Actuator
FEA Structural Analyses
Closing Thought
Boeing Seminar-3
Smart Structures
SKELETON composite/structural materials
MUSCULAR SYSTEM piezoelectric ceramics, piezoelectric polymers, shape memory alloys
SENSORY SYSTEM optical fiber sensors, piezoelectric polymer sensors, ETDR distributed strain sensors
MOTOR CONTROL SYSTEM modern distributed control algorithms
Boeing Seminar-4
Engineering Applications
Boeing Seminar-5
Smart Structures Design Philosophy
The material/structural systems can sense a need, can change based upon theneed, and can correct a mistake
Engineers will not have to learn from structural failures, but will be able tolearn from the “life experiences” of the structure.
Boeing Seminar-6
Discrete vs. Distributed Strain Sensing
Well-developed sensors currently available, such as strain gages, LVDT displacement sensors, piezoelectric transducers, Eddy current sensor, etc.
Acquiring data only at the points of interest
At the location where no sensor is present, direct measurements are not available
In practice, sensors are strategically placed at critical locations, and a mechanics-based model is used to subsequently approximate the structural response at other locations, if such data are needed
Discrete/Point Strain SensingDistributed Strain Sensing
Capable of measuring the needed data along the sensing line for the entire structure.
Having a potential to monitor integrity condition of an in-service structure, since structural failure can occur at any location.
Distributed Strain Sensors Currently Being Studied
Fiber optic sensor using Bragg grating method (quasi distributed)
Fiber optic sensor using Brillouin scattering method (true distributed, low spatial resolution, >4in)
Electrical time domain reflectometry (ETDR) strain sensor (true distributed, high spatial resolution, >0.16 in)
Boeing Seminar-7
ETDR Distributed Strain Sensing
Oscilloscope
Step Generator
Incident voltage step Reflected voltage step
Distance between the points ofmonitoring and discontinuity
Z R jL G jC [( ) / ( )] / 1 2
Z: Characteristic ImpedanceR: ResistanceL: InductanceG: ConductivityC: Capacitance
Principle of Electrical Time Domain Reflectometry (ETDR) Distributed Sensing
Fault Detection along a Power Transmission Coaxial Cable Signal Integrity Testing in an Electronic Package
Boeing Seminar-8
Coaxial Cable
Distributed Strain Sensing Mechanism
PVC jacket
tinned copper braid outer conductor
Polyethylene (or Teflon) dielectric
bare copper covered steel inner conductor
F
F
Time
Ref
lect
ion
Coe
ffici
ent
Transverse Shear
F F
Axial Tension
Time
Ref
lect
ion
Coe
ffici
ent
F F
Axial Compression
Time
Ref
lect
ion
Coe
ffici
ent
Boeing Seminar-9
Embedded ETDR Sensor
Strain Measurement
Concrete host material
crack damageCrack Damage Detection
Detection and Measurement of Stress Concentration
Boeing Seminar-10
Concrete Beam with Embedded Commercial RG-174 Coaxial Sensor Subjected to 3-Point Bending
Distance (in)71 81.5 918179.75
-0.012
-0.008
-0.004
0.000
0.004
3.40E-08 3.60E-08 3.80E-08 4.00E-08 4.20E-08 4.40E-08Time (sec)
Ref
lect
ion
Coe
ffic
ient
4 klb-in5 klb-in6 klb-in5.85 klb-in5.6 klb-in2.25 klb-in
Commercial Coaxial Cable
Capture Deformation Shape
Low Signal-to-Noise Ratio
Commercial Coaxial Sensor
Boeing Seminar-11
High Sensitivity ETDR Prototype Sensor
Polyolefin Jacket
Braid Tinned Copper Outer Conductor
Strand Tinned Copper Inner Conductor
Rubber Dielectrics
Outer Diameter ofPolyolefin Jacket
(in)
Outer Diameter ofOuter Conductor
(in)
Outer Diameterof Dielectric
(in)
Diameter ofInner Conductor
(in)
Impedance()
DielectricConstant
Large Cable 0.182 0.1606 0.1395 0.0483 40 2.8983
Small Cable 0.138 0.0985 0.0642 0.0303 40 2.7496
Boeing Seminar-12
Sensitivity Test
Clamp
ETDR Signal Triggering Unit
HP-5412T Digital Oscilloscope
High Sensitivity ETDR Prototype Sensor Subject to a Constant Spring Force of 28 lbs.
Boeing Seminar-13
Sensitivity Test (Cont.)
-0.15
-0.13
-0.11
-0.09
-0.07
-0.05
-0.03
-0.01
0.01
0.03
0.05
1.800E-08 2.200E-08 2.600E-08 3.000E-08 3.400E-08 3.800E-08
Time (sec)
Ref
lect
ion
Coe
ffic
ient
Large Prototype Cable
RG-58/U
ETDR signal sensitivity response of large prototype cable
ETDR signal sensitivity response of small prototype cable
-0.15
-0.13
-0.11
-0.09
-0.07
-0.05
-0.03
-0.01
0.01
0.03
0.05
1.80000E-08 2.20000E-08 2.60000E-08 3.00000E-08 3.40000E-08 3.80000E-08
Time (sec)
Ref
lect
ion
Coe
ffici
ent
Small Prototype Cable
RG174
Boeing Seminar-14
Tension Test
Experimental SetupComparison of ETDR signal response of high sensitivity prototype
cable and commercial RG174 cable subject to axial tension
-2.5
-2
-1.5
-1
-0.5
00 1 2 3 4 5
Strain (%)
Impe
danc
e C
hang
e (
)Prototype Cable
RG-174 Cable
Boeing Seminar-15
Reflection Coefficient
Impedance
)1()1(
1i
iii ZZ
V11
V12
V13
V14
V15
V11R2
V12R3
V13R4
V14R5
V15R6
V21
V22
V23
V24
V25
V31
V32
V33
V34
V35
V31
V41
V42
V43
V44
(1-R2)V12R3
(1-R2)(1-R3)V13R4
(1-R3)V13R4
V''31
V'21
V'22
V'23
V'24
(1-R4)V14R5
(1-R5)V15R6(1-R3)(1-R4)V14R5
(1-R2)(1-R3)(1-R4)V14R5 (1-R4)(1-R5)V15R6
V''32
V''33
V''34
V26V'25
V'26
V16
V17V16R6
V17R7V'41
V'42
V'43
V'44
V'35
])1)( 51443 RVR
V51
V52
V53
V54
V'51
V'52
V'53
Infinite Reflections
1
11,1
1,11
1
11,11,11
)1)(1(11
2
1)1()2(1)1()1(
)1(
))1((
)1()1(
)1(
])1()[()1(
i
jji
iii
i
jjiiii
nmnnmnmn
mn
niimnmnnmnnmnmn
V
VV
VVV
VVV
VVVV
Calibration of ETDR Signal Waveform
Boeing Seminar-16
Bending Response Monitoring of a Concrete Beam
Boeing Seminar-17
Bending Response - Results (Cont.)
ETDR Signal Waveforms
-0.20
-0.15
-0.10
-0.05
0.00
0 3 6 9 12 15 18 21Beam Span (in)
Def
lect
ion
(in)
LVDTETDRLoad (lbs) LVDTETDRLoad (lbs) LVDTETDRLoad (lbs)
314568766962 11661333
314568766962 11661333
Deflection Profile of the Beam
-3
-2
-1
0
22.21 23.21 24.21 25.21 26.21 27.21 28.21
Time (ns)
Impe
danc
e C
hang
e (Ω
)
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0 3 6 9 12 15 18 21
Beam Span (in)
P=314 lb
P=568 lb
P=766 lb
P=962 lb
P=1166 lb
P=1333 lb
Boeing Seminar-18
Damage DetectionETDR Signal Waveforms
Crack Damages
-3
-2
-1
0
22 24 25 27 28
Time (ns)
Impe
danc
e C
hang
e (Ω
)
-1.2
-1
-0.8
-0.6
-0.4
-0.2
0
0 5 10 15 20Beam Span (in)
1392 lbs
1420 lbs
1416 lbs
1441 lbs
1489 lbs
1499 lbs
1528 lbs
Boeing Seminar-19
In the Near Future
Field Application
Dam
Bridge
Landslide
Boeing Seminar-20
Deformation Shape Measurement
Structural Integrity Monitoring
Large Flexible Aerospace Structures
Boeing Seminar-21
Shape Measurement of Large Structure
Wooden Beam (1.5x0.2x72 in.)with Surface-Bonded High Sensitivity Prototype Cable
Experimental Setup
Fixture
ETDR Signal Triggering Unit
High Sensitivity ETDR Prototype Cable
Boeing Seminar-22
Shape Measurement of Large Structure (Cont.)
ETDR Signal Response of the Prototype Sensor
1st Mode Bending
-0.014
-0.012
-0.010
-0.008
-0.006
-0.004
-0.002
0.000
0.002
0.004
2.50E-08 3.00E-08 3.50E-08 4.00E-08 4.50E-08 5.00E-08 5.50E-08
Time (s)
Ref
lect
ion
Coe
ffici
ent
ETDR Signal
Trendline
Boeing Seminar-23
ETDR Signal Response of the Prototype Sensor
2nd Mode Bending
-0.014
-0.012
-0.010
-0.008
-0.006
-0.004
-0.002
0.000
0.002
0.004
2.50E-08 3.00E-08 3.50E-08 4.00E-08 4.50E-08 5.00E-08 5.50E-08
Time (s)
Ref
lect
ion
Coe
ffici
ent
ETDR Signal
Trendline
Shape Measurement of Large Structure (Cont.)
Boeing Seminar-24
ETDR Signal Response of the Prototype Sensor
1st Mode Reverse Bending
-0.014
-0.012
-0.010
-0.008
-0.006
-0.004
-0.002
0.000
0.002
0.004
2.50E-08 3.00E-08 3.50E-08 4.00E-08 4.50E-08 5.00E-08 5.50E-08
Time (s)
Ref
lect
ion
Coe
ffici
ent
ETDR Signal
Trendline
Shape Measurement of Large Structure (Cont.)
Boeing Seminar-25
ETDR Signal Response of the Prototype Sensor
2nd Mode Reverse Bending
-0.014
-0.012
-0.010
-0.008
-0.006
-0.004
-0.002
0.000
0.002
0.004
0.006
0.008
0.010
0.012
0.014
2.50E-08 3.00E-08 3.50E-08 4.00E-08 4.50E-08 5.00E-08 5.50E-08
Time (s)
Ref
lect
ion
Coe
ffici
ent
ETDR Signal
Trendline
Shape Measurement of Large Structure (Cont.)
Boeing Seminar-26
ETDR Film Sensor
This image cannot currently be displayed.
ETDR film sensor
To ETDR instrumentation
Laminated Composites
ETDR Film Sensor
22 in
0.5 in
Polymer FilmProtective Coating
Silver Print
110 m
Envisioned Composite Laminate with Embedded ETDR Film Sensor
Boeing Seminar-27
Impedance-Based Piezoelectric SensorHealth Monitoring and Damage Detection
•Bolted Structural Components•Adhesively Bonded Substructures•Riveted Substructures•Composite Panels (Delamination)•Engine Turbine Blades (Crack Damage)
Go, No Go ?
• Off-Duty Aircraft
• Stockpile Missile
Need Active Sensor to Interrogate the Structure
Boeing Seminar-28
Piezoelectric Sensor Piezoelectric Materials
(Two-Way Fully Coupled Electromechanical Property)
v = V sin(t) m
c
k
PZT
i = I sin(t+)
Piezo sensors convert force and motion to voltage and charge
Piezo actuators convert voltage and charge to force and motion
out
in
iv
out
in
Current) (SensingVoltage) (Actuating Impedance
Boeing Seminar-29
Damage Detection ExperimentBolt-Jointed Aluminum Cantilever Beam
200Unit: mm
Thickness of the Beam =1.7
32
48
32
48
32
ClampedAluminum BeamPiezoelectric Sensor
Experimental Set-Up
Piezoelectric Sensor
Aluminum Beam Bolt FastenerImpedance Analyzer
Tight Joint: 1 N-m Loose Joint: 0.1 N-m
Boeing Seminar-30
Experimental ResultsRepeatability Test for “Healthy” Joint (All 9 Bolts were Tightened)
0
1000
2000
3000
4000
5000
3.5 4.2 4.9 5.6 6.3 7
Frequency (KHz)
Impe
danc
e A
mpl
itude
(Ohm
s)
Test # 1
Test # 2
Test # 3
Test # 4
Boeing Seminar-31
Experimental Results (cont.)Repeatability Test for “Healthy Joint” Reference Baseline
0
1000
2000
3000
4000
5000
3.5 4.2 4.9 5.6 6.3 7
Frequency (KHz)
Impe
danc
e A
mpl
itude
(Ohm
)
All 9 Bolts Tightened
1st Bolt Loosen and Retightened
2nd Bolt Loosen and Retightened
3rd Bolt Loosen and Retightened
4th Bolt Loosen and Retightened
5th Bolt Loosen and Retightened
6th Bolt Loosen and Retightened
7th Bolt Loosen and Retightened
8th Bolt Loosen and Retightened
9th Bolt Loosen and Retightened
Boeing Seminar-32
Experimental Results (cont.)Damage Detection: 1st Bolt Loosen
0
1000
2000
3000
4000
5000
3.5 4.2 4.9 5.6 6.3 7
Frequency (KHz)
Impe
danc
e A
mpl
itude
(Ohm
)
Healthy
1st Bolt Loosen
Boeing Seminar-33
Experimental Results (cont.)Damage Detection: 1st Bolt Loosen Repeated
0
1000
2000
3000
4000
5000
3.5 4.2 4.9 5.6 6.3 7
Frequency (KHz)
Impe
danc
e A
mpl
itude
(Ohm
)
Healthy
1st Bolt Loosen
1st Bolt Loosen Repeated
Boeing Seminar-34
Experimental Results (cont.)Damage Detection: with Increasing Number of Loose Bolts
0
1000
2000
3000
4000
5000
3.5 4 4.5 5 5.5 6 6.5 7
Frequency (KHz)
Impe
danc
e (O
hm)
Healthy
One bolts loosen
Two bolts loosen
Threer bolts loosen
Four bolts loosen
Five bolts loosen
Six bolts loosen
Seven bolts loosen
Eight bolts loosen
Nine bolts loosen
Boeing Seminar-35
Experimental Results (cont.)Frequency Variation on Even Numbered Modes
3
3.5
4
4.5
5
5.5
6
6.5
7
0 1 2 3 4 5 6 7 8 9
Number of Loose Bolts
Res
onan
ce F
requ
ency
(KH
z)
S th mode S+2 th mode S+4 th mode S+6 th mode
Boeing Seminar-36
Finite Element SimulationFE Model
8-Node 3D Coupled-Field Piezoelectric Element with Ux, Uy, Uz, and V Nodal DoF
8-Node 3D Structural Brick Element with Ux, Uy, and Uz Nodal DoF2-Node 3D Structural
Spar Element with Ux, Uy, and Uz Nodal DoF
Aluminum Beam 1 Aluminum Beam 2
Piezoceramic Sensor
Harmonic Response Analysis -> Applied Load: Nodal Voltage, Vosin(t)Output: Nodal Charge
Boeing Seminar-37
Piezoelectric Constitutive Equation
jijjkijki
mmijklijklij
EeqEeD
ij stress tensorij strain tensor Ei electric field vector qi electric flux density vector Dijkl elastic stiffness tensor (evaluated at constant electric field)ij dielectric tensor (evaluated at constant mechanical strain)
lmjkilmijk Dde piezoelectric stress coefficient tensor ilmd piezoelectric strain coefficient tensor.
Boeing Seminar-38
FEA-Experiment ComparisonImpedance Spectrum of the Healthy Joint
0
1000
2000
3000
4000
5000
3.5 4 4.5 5 5.5 6 6.5 7
Frequency (KHz)
Impe
danc
e (O
hm)
FEA
Experiment
Boeing Seminar-39
Hybrid Linear/Rotary Stepper Motor (Cont.)
Rotary Driver (at disengaged
position)
Linear Driver
y
z
x
z
Linear Driver
Rotary Driver (at disengaged
position)
1 3 1 3 1 3 1 31 3
2 42 42 42 42 4
Power-Off Position Step 1 Step 2 Step 3 Step 4
Boeing Seminar-40
Hybrid Linear/Rotary Stepper Motor (Cont.)
2
1
3
42
1
3
4
Step 2 Step 3 Step 4
2
1
3
4
Core RodCore Rod
Core RodCore Rod
2
Actuator 1
Actuator 3
4
Step 1Power-Off Position
2
1
3
4
Core Rod
Boeing Seminar-41
Concept DemonstrationMotor Assembly
Normal Mode PZT actuator
Aluminum motor core shaft (0.5”x0.5”x6”)
Aluminum retaining wall
Plexiglas insulating shoe
Shear Mode PZT actuator d33 mode element
d15 mode element
glass insulation shoe
-2000
-1500
-1000
-500
0
500
1000
0 5 10 15 20 25 30
Time (sec.)
Vol
tage
(v)
V3 V1
V3' V1'
Driving Signal
Multi-channel filter
PC based multi-channelfunction generator
Driver 1PZT element d31 griping
Driver 1PZT element
d15 shear
Driver 2PZT element d31 griping
Driver 2PZT element
d15 shear
HV amplifier HV amplifier HV amplifier HV amplifier
Boeing Seminar-42
It Moved!
-25
-20
-15
-10
-5
0
5
10
15
20
25
0 0.2 0.4 0.6 0.8 1
Time (sec.)
Dis
plac
emen
t (m
)
1 Hz
3 Hz
5 Hz
10 Hz
20 Hz
forward motion
backward motion
Driving Frequency (Hz) 1 3 5 10 20
Motor Core Velocity (m/s) 1.2 3.8 6.8 12.4 21.8
Boeing Seminar-43
Shape Memory Alloy (Nitinol) Actuator
• Variable Structural Stiffness for Natural Mode Tuning to Avoid Flutter
• Active Shape Control to Improve Aeroelastic Effectiveness
Shape Memory Alloy (SMA)
Boeing Seminar-44
Adaptive Stress Alleviation of Pressure Vessel
SMA Hybrid Composites Pressure Vessel
Composite cylinder with a layer of SMA actuator
Activation of the SMA layer induces shrinkage against the cylinder
The induced pressure by the SMA layer creates the compound cylinder effect, resulting in structural stress alleviation on the composite cylinder
SMA ActuatorComposite Pressure Vessel
Boeing Seminar-45
0
30
60
90
120
150
50 100 150 200 250 300
Activation Temperature (°F)
Hoo
p St
ress
(ksi
)
R = 0.005
R = 0.495
R = 0.505
R = 0.995
• Significant stress alleviation can be achieved on a graphite/epoxy pressure vessel with a 1.5% recoverable prestrain of the SMA actuator
Hoop Stress at Various Locations along the Cylinder Walla Function of Activation Temperature of the SMA
Adaptive Stress Alleviation of Pressure Vessel
Boeing Seminar-46
Smart Materials & Structures
We cannot create life,
but can learn from life
to save life.
Boeing Seminar-47
FEA of a Solar Sail Membrane
pp
circular membrane d = 10 m thickness = 7.6 microns partially illuminated light pressure with
an oblique incident angle of 35
Induced radial displacement contourInduced radial stress contour
Boeing Seminar-48
FEA Modeling of a Spindle Lug
Boeing Seminar-49
Background
Crack failure occurred on the trailing lower lug
Crack damage appears to initiate at the bushing/lug interface
Fatigue and possibly fretting fatigue origins were SEM observed
No root cause for the premature failure has been identified
Boeing Seminar-50
FE Static Analysis
FEA Constraint and Load Conditions
70,000 lbs total load applied Surface Pressure
Boeing Seminar-51
FEA Results
Tension Load = 29,000 lb , P = 3,200 psi
Principal Stress Contour Von Mises Contour
Boeing Seminar-52
Indoor(Controlled Climate)
Outdoor(Changing Climate) Concrete
(Porous)
FRP (Permeable)
Hygrothermal Stress and Moisture Damage at the Interface -> Delamination
Unreinforced Masonry Wall with FRP Reinforcement Upgrade
FEA Modeling of Hygro-Thermo-Mechanical Response of a Fiber Reinforced Polymer Composites Reinforcement
Boeing Seminar-53
Heat and Moisture Transport Model
h Relative humidity of the ambient air (dimensionless)
Vapor resistivity of the media (dimensionless)
p Vapor permeability of the air (kg/m s Pa)
Ps Saturation vapor pressure (Pa)
ASTM version (2001)
)]([)( sP hPD
t
)]([)( sP
v hPhTtTc
All parameters are well defined and physically measurable.
Boeing Seminar-54
Finite Element Modeling Finite element formulation in terms of nodal values
ee
ee
e
ee Q
Th
DTh
C
][][ **
where: ),,( zyxN = vector of shape functions
e
e
Th
= nodal humidty/temperature vector
dVBDBDV
Te ][][][][ ** element humidity and heat diffusion matrix
dVNN
cC
C T
Ve 00
][ *
* element humidity and heat capacity matrix
dSqNQSe
* element boundary humidity and heat flux
TNLB ][
0* Th DD
D = Humidity and heat diffusion matrix
The Finite element formulation is implemented in FEMLAB computer software.
Boeing Seminar-55
Case Study: Results
Transient relative humidity profile for Tout=40oC at Tin=20oC along the centerline at X=198 mm
40
50
60
70
80
90
100
0 3.88 7.76 11.64 15.52 19.4 23.28 27.16 31.04 34.92 38.8X (mm)
Rel
ativ
e H
umid
ity (%
)
40
50
60
70
80
90
100-194 -155.2 -116.4 -77.6 -38.8 0 38.8 77.6 116.4 155.2 194
1 day 5 days 20 days 1 month 2 months
3 months 5 months 10 months Steady State
FRP Concrete
Boeing Seminar-56
Hygro-Thermally Induced Interfacial StressesFinite Element Formulation
thermalswellingtotalelastic DD T
refrefrefthermal TTTTTT 000)()()( 321
where:i the thermal expansion coefficients
in the principle material directions i = 1,2,3
refT = the reference (strain-free) temperature
wvu
LTxzzyzxyzyxtotal
T
xyz
zxy
zyx
L
000
000
000
Trefrefrefswelling 000)()()( 321
Boeing Seminar-57
Finite Element Formulation swellingthermalSB FFFFUK ][
where:
Trrr wvuwvuwvuU ...222111 = nodal displacement vector
dVBDBKV
T ][][][][ = element stiffness matrix
dVFNF bV
TB ][ = element body force vector
dSFNF sS
TS ][ = element force due to the surface loading
dVDBF thermalV
Tthermal ][][ = element force vector due to the thermal expansion
dVDBF swellingV
Tswelling ][][ = element force vector due to the moisture swelling
TNLB ][
T
r
r
r
NNNNNN
NNNzyxN
00...000000...000000...0000
),,(
21
21
21
= shape function matrix
The Finite element formulation is implemented in FEMLAB computer software.
Boeing Seminar-58
-100
0
100
200
300
400
500
600
40 60 80 100 120 140 160 180 200
Z (mm)
Szy
(kPa
)
Tout = 10o C
Tout = 20o C
Tout = 40o C
Tout = 60o C
FEA ResultsInterfacial shear stress, yz, distribution for various outdoor temperatures along the z-axis
at x = 198 mm in FRP laminate
Boeing Seminar-59
-400
-200
0
200
400
600
800
1000
1200
198 208 218 228 238 248 258 268 278 288 298 308 318
X (mm)
y (k
Pa)
Tout = 10o C
Tout = 20o C
Tout = 40o C
Tout = 60o C
FEA Results (cont.)Peeling stress, y, distribution for various outdoor temperatures along the z-axis at
x = 198 mm in FRP laminate